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Java > Open Source Codes > org > jfree > data > jdbc > JDBCPieDataset


1 /* ===========================================================
2  * JFreeChart : a free chart library for the Java(tm) platform
3  * ===========================================================
4  *
5  * (C) Copyright 2000-2005, by Object Refinery Limited and Contributors.
6  *
7  * Project Info: http://www.jfree.org/jfreechart/index.html
8  *
9  * This library is free software; you can redistribute it and/or modify it
10  * under the terms of the GNU Lesser General Public License as published by
11  * the Free Software Foundation; either version 2.1 of the License, or
12  * (at your option) any later version.
13  *
14  * This library is distributed in the hope that it will be useful, but
15  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
16  * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
17  * License for more details.
18  *
19  * You should have received a copy of the GNU Lesser General Public
20  * License along with this library; if not, write to the Free Software
21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
22  * USA.
23  *
24  * [Java is a trademark or registered trademark of Sun Microsystems, Inc.
25  * in the United States and other countries.]
26  *
27  * -------------------
28  * JDBCPieDataset.java
29  * -------------------
30  * (C) Copyright 2002-2004, by Bryan Scott and Contributors.
31  *
32  * Original Author: Bryan Scott; Andy
33  * Contributor(s): David Gilbert (for Object Refinery Limited);
34  * Thomas Morgner;
35  *
36  * $ Id: $
37  *
38  * Changes
39  * -------
40  * 26-Apr-2002 : Creation based on JdbcXYDataSet, but extending
41  * DefaultPieDataset (BS);
42  * 24-Jun-2002 : Removed unnecessary import and local variable (DG);
43  * 13-Aug-2002 : Updated Javadoc comments and imports, removed default
44  * constructor (DG);
45  * 18-Sep-2002 : Updated to support BIGINT (BS);
46  * 21-Jan-2003 : Renamed JdbcPieDataset --> JDBCPieDataset (DG);
47  * 03-Feb-2003 : Added Types.DECIMAL (see bug report 677814) (DG);
48  * 05-Jun-2003 : Updated to support TIME, optimised executeQuery method (BS);
49  * 30-Jul-2003 : Added empty contructor and executeQuery(connection,string)
50  * method (BS);
51  * 02-Dec-2003 : Throwing exceptions allows to handle errors, removed default
52  * constructor, as without a connection, a query can never be
53  * executed (TM);
54  * 04-Dec-2003 : Added missing Javadocs (DG);
55  */
56
57 package org.jfree.data.jdbc;
58
59 import java.sql.Connection JavaDoc;
60 import java.sql.DriverManager JavaDoc;
61 import java.sql.SQLException JavaDoc;
62 import java.sql.Timestamp JavaDoc;
63 import java.sql.Types JavaDoc;
64 import java.sql.ResultSet JavaDoc;
65 import java.sql.ResultSetMetaData JavaDoc;
66 import java.sql.Statement JavaDoc;
67
68 import org.jfree.data.general.DefaultPieDataset;
69 import org.jfree.data.general.PieDataset;
70
71 /**
72  * A {@link PieDataset} that reads data from a database via JDBC.
73  * <P>
74  * A query should be supplied that returns data in two columns, the first
75  * containing VARCHAR data, and the second containing numerical data. The
76  * data is cached in-memory and can be refreshed at any time.
77  *
78  * @author Bryan Scott.
79  */
80 public class JDBCPieDataset extends DefaultPieDataset {
81
82     /** The database connection. */
83     private transient Connection JavaDoc connection;
84
85     /**
86      * Creates a new JDBCPieDataset and establishes a new database connection.
87      *
88      * @param url the URL of the database connection.
89      * @param driverName the database driver class name.
90      * @param user the database user.
91      * @param password the database users password.
92      *
93      * @throws ClassNotFoundException if the driver cannot be found.
94      * @throws SQLException if there is a problem obtaining a database
95      * connection.
96      */
97     public JDBCPieDataset(String JavaDoc url,
98                           String JavaDoc driverName,
99                           String JavaDoc user,
100                           String JavaDoc password)
101         throws SQLException JavaDoc, ClassNotFoundException JavaDoc {
102         
103         Class.forName(driverName);
104         this.connection = DriverManager.getConnection(url, user, password);
105     }
106
107     /**
108      * Creates a new JDBCPieDataset using a pre-existing database connection.
109      * <P>
110      * The dataset is initially empty, since no query has been supplied yet.
111      *
112      * @param con the database connection.
113      */
114     public JDBCPieDataset(Connection JavaDoc con) {
115         if (con == null) {
116             throw new NullPointerException JavaDoc("A connection must be supplied.");
117         }
118         this.connection = con;
119     }
120
121
122     /**
123      * Creates a new JDBCPieDataset using a pre-existing database connection.
124      * <P>
125      * The dataset is initialised with the supplied query.
126      *
127      * @param con the database connection.
128      * @param query the database connection.
129      *
130      * @throws SQLException if there is a problem executing the query.
131      */
132     public JDBCPieDataset(Connection JavaDoc con, String JavaDoc query) throws SQLException JavaDoc {
133         this(con);
134         executeQuery(query);
135     }
136
137     /**
138      * ExecuteQuery will attempt execute the query passed to it against the
139      * existing database connection. If no connection exists then no action
140      * is taken.
141      * The results from the query are extracted and cached locally, thus
142      * applying an upper limit on how many rows can be retrieved successfully.
143      *
144      * @param query the query to be executed.
145      *
146      * @throws SQLException if there is a problem executing the query.
147      */
148     public void executeQuery(String JavaDoc query) throws SQLException JavaDoc {
149       executeQuery(this.connection, query);
150     }
151
152     /**
153      * ExecuteQuery will attempt execute the query passed to it against the
154      * existing database connection. If no connection exists then no action
155      * is taken.
156      * The results from the query are extracted and cached locally, thus
157      * applying an upper limit on how many rows can be retrieved successfully.
158      *
159      * @param query the query to be executed
160      * @param con the connection the query is to be executed against
161      *
162      * @throws SQLException if there is a problem executing the query.
163      */
164     public void executeQuery(Connection JavaDoc con, String JavaDoc query) throws SQLException JavaDoc {
165
166         Statement JavaDoc statement = null;
167         ResultSet JavaDoc resultSet = null;
168
169         try {
170             statement = con.createStatement();
171             resultSet = statement.executeQuery(query);
172             ResultSetMetaData JavaDoc metaData = resultSet.getMetaData();
173
174             int columnCount = metaData.getColumnCount();
175             if (columnCount != 2) {
176                 throw new SQLException JavaDoc(
177                     "Invalid sql generated. PieDataSet requires 2 columns only"
178                 );
179             }
180
181             int columnType = metaData.getColumnType(2);
182             double value = Double.NaN;
183             while (resultSet.next()) {
184                 Comparable JavaDoc key = resultSet.getString(1);
185                 switch (columnType) {
186                     case Types.NUMERIC:
187                     case Types.REAL:
188                     case Types.INTEGER:
189                     case Types.DOUBLE:
190                     case Types.FLOAT:
191                     case Types.DECIMAL:
192                     case Types.BIGINT:
193                         value = resultSet.getDouble(2);
194                         setValue(key, value);
195                         break;
196
197                     case Types.DATE:
198                     case Types.TIME:
199                     case Types.TIMESTAMP:
200                         Timestamp JavaDoc date = resultSet.getTimestamp(2);
201                         value = date.getTime();
202                         setValue(key, value);
203                         break;
204
205                     default:
206                         System.err.println(
207                             "JDBCPieDataset - unknown data type"
208                         );
209                         break;
210                 }
211             }
212
213             fireDatasetChanged();
214
215         }
216         finally {
217             if (resultSet != null) {
218                 try {
219                     resultSet.close();
220                 }
221                 catch (Exception JavaDoc e) {
222                     System.err.println("JDBCPieDataset: swallowing exception.");
223                 }
224             }
225             if (statement != null) {
226                 try {
227                     statement.close();
228                 }
229                 catch (Exception JavaDoc e) {
230                     System.err.println("JDBCPieDataset: swallowing exception.");
231                 }
232             }
233         }
234     }
235
236
237     /**
238      * Close the database connection
239      */
240     public void close() {
241         try {
242             this.connection.close();
243         }
244         catch (Exception JavaDoc e) {
245             System.err.println("JdbcXYDataset: swallowing exception.");
246         }
247     }
248 }
249
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